The parents of a slain Bay Terrace police officer have sued a Long Island auto dealership for $25 million, alleging it "did nothing" to prevent an employed felon from taking the sport utility vehicle used in their son's murder.

Dexter Bostic, 36, and criminal cohorts had unfettered access to on-site vehicles at Five Towns Mitsubishi in Inwood, contended Leonid and Tatyana Timoshenko, the parents of Russel Timoshenko.

Bostic, a convicted robber and sex offender on parole, was a salesman at the dealership, also known as Airport Auto Group, Inc.

On July 9, 2007, Bostic fatally shot Timoshenko, 23, during a traffic stop in Brooklyn.

Timoshenko and his partner, Officer Herman Yan, had stopped a BMW SUV around 2:30 a.m. in the Prospect-Lefferts Garden section because the license plates were from another car.

Bostic was a passenger in the vehicle, which, police said, was stolen from Five Towns Mitsubishi.

Another passenger, Robert Ellis, 36, Bostic's roommate, who once worked at the dealership, shot and wounded Yan, said police. A third defendant, Lee Woods, 31, was behind the wheel, police said.

Three separate juries in Brooklyn convicted Bostic and Woods of murder; Ellis was found guilty of weapon possession.

Bostic and Woods were sentenced earlier this year to life without parole. Ellis, who was acquitted of murder and attempted murder, received 15 years. All three defendants were Queens residents.

The civil suit, filed in state Supreme Court, St. George, seeks $20 million for wrongful death and $5 million for conscious pain and suffering. Timoshenko, a Tottenville High School graduate and native of Belarus, was on life support for five days before succumbing to his wounds.

He was posthumously promoted to detective.

Five Towns Mitsubishi and Airport Auto Group are named defendants along with alleged company principals.

The Timoshenkos' lawyer, Alec Sauchik of Brooklyn, did not immediately return a telephone call last week seeking comment.

Telephone numbers obtained for Five Towns Mitsubishi are no longer in service. There is no telephone listing in Inwood for Airport Auto Group.

The Timoshenkos allege the dealership was undercapitalized and shoddily run.

Bostic, also known as "Marcus Jackson" was hired to sell cars despite "multiple" violent-felony convictions and being on parole. According to state Department of Correctional Services online records, he had served time twice: During most of the 1990s for assault, sodomy and robbery and later for attempted weapon possession.

Bostic took dealership vehicles as he pleased and also gave other felons access to them, the Timoshenkos contend. They allege the vehicles were sometimes used for crimes, yet the dealership turned a blind eye.

The defendants "did nothing to prevent Bostic from having full and unrestricted access to the dealership's inventory vehicles at any time," allege the Timoshenkos.

The murder was set in motion when Bostic entered the dealership off-hours on July 9, 2007, court papers said.

He removed the keys for an unregistered BMW X5 from an unlocked box, then, along with his accomplices, attached license plates to it that were registered to a Mitsubishi SUV, court papers said. Armed with at least three illegal handguns and a machine pistol, they drove off, eventually heading into Brooklyn.

Officials said the men previously had removed cars from the lot and cruised the metropolitan area before returning them. Bostic had done so the day before the fatal shooting, when, police suspect, he used a sports car in a drive-by shooting in Queens.